Solution!
I had the same issue , multi monitor setup , double headed arrow and could only resize windows but not move etc. The issue is related to different resolutions accross multi monitors. Tried same trouble shooting as op.
What worked for me was too force myob to open on the hi-res monitor not the laptop screen.
I set the hi-res monitor as my default screen (system/display/select monitor/make this my main display) , re opened myob and fixed.
*did try saving the window location via holding shift or ctr while closing myob but wouldn't save.
Hope this helps someone , because myob tech support couldn't
